Aluminum catalyst



. Patented Oct. 13, 1936 PATENT OFFICE ALUMINUM CATALYST FriedrichMartin, Oberhausen, Walter Grimme,

Oberhausen-Sterkrade, and Alfred Kiippelmann, Oberhausen-Holten, GermanyNo Drawing. Application pril is, 1935, Serial No. 11,132. In GermanyApril 24, 1934 12 claims. (area-9s) Our invention relates to catalystsand more especially to the well known aluminum chloride catalyst used inquite a number of reactions including the so-called Friedel-Craitsreaction,

cracking and hydrogenation reactions etc. It is an object or ourinvention to provide means whereby an aluminum chloride catalyst can beproduced which is more efllcient than similar catalysts hitherto in use.

10 Our invention also relates to the reactions carried through with thenew catalyst and quite especially to reactions of the Friedel-Craitstype, which are greatly improved by the use or an aluminum chlorideproduced in accordance with this invention.

With this and other objects in view we are now going to describe ourinvention and the way in which it is carried out.

As is well known, reactions of the Friedel- Crafts type, but alsohydrogenation reactions re.-

quire the use of an anhydrous aluminum chloride and it is equally knownthat in the production,"

and storage of this substance considerable dimculties are encountered.g5 We have now found that there is no'necessity for using the ready madealuminumchloride of commerce, but that it is very advantageous, it

starting a reaction of the Friedel-Crafts type, to

produce the aluminum chloride catalyst in situ, i. e. inthe reactionmixture.

The Friedel-Craits reaction is the reaction be- 40 eluding toluene andxylene, further naphthalene, j

anthracene and their homologues may be used. The reaction is alsocarried through with in-, completely hydrogenated aromatic hydrocarbonssuch as tetralin, with aryl-substituted aliphatic 5 hydrocarbons, suchas 'diphenylmethane,

benzyl, bi-phenyl and its homologues, such as ditolyl. The reactions mayfurther be varied by replacing the aromatic hydrocarbon by its'alkoxyderivatives, i. e. the ethers of univalent or 5o polyvalent phenols,such as anisol or naphthene ether; one or more hydrogen atoms in thenucleus of the aromatic hydrocarbon may be substituted by halogen.Instead of an aromatic hydrocarbon thiophene may also be used.

It reacting an aromatic hydrocarbon with a with halogen in the sidechain. Thus for instance if reacting benzene with benzylchloride, di-

phenylmethane is obtained. An aromatic hy- 1Q drocarbon may further bereacted with an unsaturated aliphatic hydrocarbon, such as ethyl- ,ene,propylene 'or butylene, whereby aromatic hydrocarbons with a side chainare obtained, benzene and ethylene furnishing ethylbenzene, 16 benzeneand propylene, propylbenzene. On the other hand unsaturated aromatichydrocarbons may be used having an unsaturated side chain, sifih asstyrene, which when reacted with benzene leads to the formation ofdiph'enylethane. g0 When acting on anaromatic hydrocarbon with anacid'chloride or an acid anhydrid, one obtains a keton. The acidchloride may be substituted by halogen or the nitro group.

Hitherto the reaction between substances of 35 the kind aforesaid wascarried out inthe presence a of anhydrous aluminum chloride produced inany suitable manner by acting on aluminum metal with hydrochloric acid.It acting on the metal with hydrochloric acid gas in theabsence 01' 30any solvent, the aluminum chloride will form at a high temperature above100 and even 200 C. If acting on aluminum metal with the hydrochloricacid gas at normal or moderately raised temperatures no reaction willoccur even though 35 the, aluminum may be suspended in benzene, benzine,carbon-disulflde or the like. The reaction between the metal and theacid may be inpromoted to a surprising degree. 50

Thus for instance, if aluminum powder is suspended in benzene andhydrogen chloride gas is introduced into the suspension, no reactionwill take place between the metal and the acids. How ever it a smallquantity, for instance not exceed- In-B ing 3% by weight of the metal,of anhydrous sublimated aluminum chloride is added, the mixture willheat up and a vigorous formation of hydrogen will set in soon after thealuminum chloride has been added. After a short period of time thealuminum metal will have disappeared, being converted into aluminumchloride. At a temperature which will as a rule be between 50 and 70 C.,but which may in some cases be raised up to 250 C., the velocity of thereaction -is greatly increased. Obviously the appropriate temperaturewill depend in each individual case from the boiling temperature of thecomponents of the reaction mixture and from the pressure. When operatingat ordinary pressure and using benzene as one of the components of aFriedel- Crafts reaction, a temperature of 70 C. will practically not beexceeded. If operating under increased pressure, for instance whenproducing ethyl benzene by the interaction of benzene,

ethylene and aluminum chloride, materially higher temperatures may befound useful.

We have found it particularly useful to produce the aluminum chloride inthe course of a reaction of the Friedel-Crafts type or, at least, toproduce it in a medium forming one of the constituents of such areaction mixture. In thus proceeding we obtain an aluminum chloridepossessing a surprisingly great reactivity and which is capable offavorably influencing the reaction, whether of the Friedel-Crafts typeor of the cracking or hydrogenation type. which it is intended to carrythrough with .its use.

In the practice of our invention we cause aluminum powder to react withdry hydrogen chloride gas in the presence of an aromatic hydrocarbon orsome other liquid capable of participating in a reaction according tothe Friedel-Crafts We have found that the reaction between the aluminumand the hydrogen chloride will set in only if a catalyst is present,which may either be some aluminum chloride previously formed or a doublesalt of thealuminum chloride such as potassium aluminum chloride or adouble compound of aluminum chloride with an unsaturated aliphatic oraromatic hydrocarbon such as ethylene, propylene etc. or ethylbenzene.Of such double compounds only the combination of 1 molecule ethylene and1 molecule aluminum chloride constituted according to the formulaA1C1a.CaH4 has been-described.

As soon as a small quantity of such a catalyst is added to the mixture,a vigorous generation of hydrogen will set in and the aluminum metal isdissolved, aluminum chloride being formed.

We have found it particularly useful to add a double compound ofaluminum chloride and a hydrocarbon, since these compounds have thecharacter of oils, which are capable of dissolving the freshly formedaluminum chloride, which is thus removed from the aluminum metal, sothat a bright metallic surface is always exposed to the action of thehydrogen chloride gas.

The conversion .of the aluminum metal into aluminum chloride will as arule be terminated after the lapse of a few hours, say from 2 to 5hours.

In practicing our invention we may for instance proceed as follows:

Ezample 1 15 grams aluminum powder and 1 to 2 grams anhydrous sublimatedaluminum chloride are entered into 300 cubic centimetre drv benzene ofhydrogen chloride has been stopped.

Example 2 If the mixture described with reference to Example 1 is heatedfrom the beginning to about 70 C. under the reflux condenser, about ofthe aluminum metal will have been converted into the anhydrous chlorideafter the lapse of not more than 2 hours.

Example 3 If the pure aluminum chloride in the reaction mixturedescribed with reference to Example 1 is replaced by 3 grams potassiumaluminum chloride, the conversion of the metal into the chloride willoccur similarly as described with reference to Examples 1 and 2.

Example 4 If the pure aluminum chloride is replaced by 3 grams of anoily double compound formed from aluminum chloride and ethyl benzene,the reaction between the aluminum metal and the hydrogen chloride willproceed particularly quickly.

Example 5 Into a mixture of 200 grams benzene, 30 grams aluminum metaland 4 grams aluminum chloride, hydrogen chloride gas is introduced undervigorous stirring and heating, until about one half of the metal hasbeen converted into the chloride, whereupon 40 grams acetylchloride areadded. The hydrochloric acid, liberated in the vehement reaction whichnew sets in, quickly dissolves the bulk of the aluminum metal which hadremained over. From the product of reaction 25 grams acetophenon can berecovered.

The above description will have shown that by causing the aluminumchloride required as a catalyst in the Friedel-Crafts and otherreactions to be formed in situ, i. e. in a medium capable of enteringone of these reactions and more especially the Friedel-Crafts reaction,the conversion of the metal into the chloride is greatly expedited and acatalyst obtained, the reactive properties of which far exceed those ofthe anhydrous aluminum chloride produced according to old methods.

Quite particularly the addition products of aluminum chloride and one ofthe hydrocarbons here in question have proved to be particularlysuitable for use in the conversion of the aluminum metal into thechloride.

While in the examples benzene has been used,

obviously all the other constituents of a Friedel- Crafts reactionmixture'may be used to suspend the aluminumin. We may as well use thehomologues of benzene including toluene and'xylene,

. as also compounds containing a combination of nuclei, such asnaphthalene, anthracene and their homologues, incompletely hydrogenatedarosmatic hydrocarbons such as tetrahydrona'ph thalene (tetralin) oraliphatic hydrocarbons substituted by-aromatic radicles such asdiphenylmethane 'or diphenyl and the homologues of these hydrocarbons;Instead of the hydrocarbons themselves we may use their alkoxyderivatives orftheir halogen substitution products or thiophene.

Variouschanges may be made in the details disclosed in the foregoingspecification without departing from the invention or sacrificing theadvantages thereof.

In the claims aiiixed to this specification no selection ofanyparticularmodiflcationcf, the invention is "intended to. the exclusion of othermodifications thereof and the right to subsequently make claim inthe'present' application toany I Y J modification not covered by theseclaims i xpressly reserved-..

i so,

- 1. The method of producing a catalyst which We claim:--

comprises reacting aluminum .metal with dry hydrogen chloride gas in thepresence initially of a small quantity of an aluminum chloride catalystin a medium capable of undergoing a reaction of the Friedel-Crafts type.

2. The method of producing a catalyst which comprisese reacting aluminummetal with dry hydrogen chloride gas in the presence initially of asmall quantity of anhydrous aluminum chloride in a medium capable ofundergoing a reaction of the Friedel-Crafts type.

*cso.

.drogen chloride gas in the presence initially of a small quanti y ofpotassium aluminum chloride 3. The method of producing a catalyst whichcomprises reacting aluminum metal with dry hydrogen chloride gas in thepresence initially at a small quantity of a double salt of aluminumchloride in a medium capable of undergoing a reaction of theFriedel-Crafts tyre.

4. The method of producing a catalyst which comprises reacting aluminummetal with dry hyin a medium capable of undergoing a reaction of theFriedel-Crafts type.

5. The method of producing a catalyst which 7 comprises reactingaluminum-metal with dry hy- Y drogen chloride gas in the presenceinitially o! a small quantity of an add.tion compound of aluminumchloride and an unsaturated hydrocarbon ina medium capable of undergoinga reaction of the Friedel-Crafts type.

6. The method of producing a catalyst which comprises reacting aluminummetal with dry hydrogen chloride gas in the presence initially of a.small quantity of aluminum chloride and an unsaturated aliphatichydrocarbon in a medium ca- "pable of undergoing a reaction of theFriedel- Crafts type. a

' 7. The method of producing a catalyst which comprises reactingaluminum metal with dry hychloride with dry hydrogen chloride gas in acompound of the naphthalene series.

10. The method of producing a catalyst which comprises reacting aluminummetal in the presence initially of a small quantity or aluminum chloridewith dry hydrogen chloride gas in a compound of the anthracene series.

11. The method of producing a catalyst which comprises reacting aluminummetal in the presence initially of a small quantity of aluminum Ichloride with dry hydrogen chloride gas in a Friedel-Cratts reactionmixture.

12. The method of producing a catalyst which comprises reacting aluminummetal in the presence initially of a small quantity of aluminum chloridewith dry hydrogen chloride gas in a mixture of compounds undergoing areaction of the Friedel-Craits type.

WALTER GRIMME. ammo xorrnummw.

